Nadal fought back from two sets down and saved four match points in a 135-minute minute fifth set in which he successfully served to stay alive nine times, but it was not enough.
Rafael Nadal's challenge for a third Wimbledon crown ended in heart-breaking fashion as relentless Luxembourger Gilles Muller won a nerve-jangling fourth-round classic 6-3 6-4 3-6 4-6 15-13 on Monday.
The 31-year-old Nadal fought back from two sets down and saved four match points in a 135-minute minute fifth set in which he successfully served to stay alive nine times.
At the 10th time of asking, however, and with thousands of transfixed fans watching the drama unfold on the screen on the hill and on the edge of their seats on Court One, Nadal buckled under the relentless pressure exerted by an inspired Muller.
A miss-hit forehand gave Muller two more match points and this time he finished the job as a weary Nadal went long.
Sixteenth seed Muller, who served 30 aces and hit 95 winners, will play Marin Cilic in the quarter-finals.
"I'm just glad it's over," the 34-year-old Muller, who claimed a second Wimbledon win over Nadal having beaten him at the All England Club in 2005, said.
"I did really well in the first two sets, then Rafa stepped it up. It was a big battle. When I had the last two match points, I thought I just had to give it a shot."
Muller outplayed 15-times grand slam champion Nadal in the opening two sets but when the Spaniard fired himself up and began to play his best tennis it seemed his chance had gone.
Prince Felix watching
With Prince Felix of Luxembourg watching in the stands, Muller showed remarkable resolve to withstand the Nadal fightback and keep his nose in front in the fifth set.
He saw two match points come and go in the 10th game, saved break points at 6-6 and 9-9 as Nadal turned the screws, and then secured the biggest victory of his career to reach the last eight at Wimbledon for the first time.
Novak Djokovic's fourth round match against France's Adrian Mannarino was postponed until Tuesday after the marathon battle between Nadal and Muller finished late on Monday.
Djokovic was due to follow Nadal on Court Number One but the Spaniard's defeat to Muller lasted four hours 47 minutes and made it impossible for the Serb's match to be completed before dark.
Canada's Milos Raonic survived a marathon fourth round workout against rising German star Alexander Zverev, knocking out some pundits' outside bet for this year's title 4-6 7-5 4-6 7-5 6-1.
Seeded sixth and runner-up last year to Andy Murray, Raonic kept his cool on the crunch points, taking five of eight opportunities to break while the 20-year-old 10th seed converted just three of 18.
The big-serving Canadian sealed the match with his 23rd ace after close to 3-1/2 hours' play.
Raonic will face Roger Federer in Wednesday's quarter-final.
Quest for 8th crown
Federer kept his quest for a record eighth Wimbledon crown on track by dispatching Grigor Dimitrov 6-4 6-2 6-4 in a match-up of classic styles that had the purists purring.
The Bulgarian 13th seed, nicknamed "Baby Fed" when he was a junior on the basis of a single-handed backhand as silkily smooth as the Swiss master's, looked sharp in the early exchanges.
It was close to mirror-image tennis as the two men exchanged searing groundstrokes, gliding to the Centre Court net when they saw an opening to dispatch clinical volleys.
But the difference between the greatest ever player on grass and the man who has struggled for years to emerge from his shadow told on the big points.
Third seed Federer, who missed the clay court season to better prepare for his favourite tournament, took a decisive lead in the ninth game, converting his third break point. The Swiss then served out the first set to love.
"(Dimitrov) did give me some opportunities ... but most important was for me to really focus on my game," Federer told the BBC after the match.
"I thought it was a terrific match and I didn't expect it to go that easy for me."
Now 26 and seeking his first win against Federer in six matches, Dimitrov sought to up the pace in the second set.
But as he did so the Bulgarian's error count also rose, and he conceded the second set on a break of serve, punctuating a double fault with two forehands that flew long.
That pattern continued in the third set as another forehand error from Dimitrov handed Federer victory on his second match point in just over an hour and a half.
Defending champion Andy Murray eased into the Wimbledon quarter-finals for the 10th successive year with a 7-6(1) 6-4 6-4 victory over Benoit Paire while seventh seeded Croat Marin Cilic demolished Roberto Bautista Agut 6-2 6-2 6-2 to reach the quarterfinals.
The in-form Croat, runner-up at the Queen's Club warm-up tournament last month, wobbled a little as he served for a place in the last eight, with the Spaniard saving three match points.
But Cilic sealed the match on the fourth with a big serve that Bautista Agut could only parry into the net.
It is the fourth time in a row that Cilic has reached the Wimbledon quarter-finals and he has rarely looked more comfortable.
He will face Muller in the quarterfinals.